Introduction. Urolithiasis remains one of the most common diseases in the pediatric urology practice. A special category is made up of children weighing up to 15 kg with large and coral-like kidney stones, which require a smaller instrument to remove.

Aim. The aim of the study was to evaluate the effectiveness of percutaneous nephrolithotripsy, used for urolithiasis treatment in children aged 1 to 3 years.

Materials and methods. Between 2008 and 2019 in the pediatric uroandrology department of the National Medical Research Radiological Centre of the Ministry of Health of the Russian Federation 93 children aged 1 to 3 years (69 (74.2%) boys and 24 (25.8%) girls) had nephrolithotripsy. The average patients age was 1 year and 9 months. Fifty-one (54.8%) patients had coral-like kidney stones, while the remaining 42 (45.2%) had kidney pelvic stones. The average stone size was 25.8mm. (15 – 56 mm). Nephrolithotripsy was performed according to the standard technique, all patients underwent cystoscopy and ureteral catheterization. In the prone position, under ultrasound and X-ray guidance, a puncture of the renal collecting system was performed. In 59 cases (63.5.1%) the puncture was performed through the lower calyx, in 31 cases (33.3%) – through the middle one, and in nine children two approaches were performed. In 93 children the intervention was performed using a mininephroscope with tubes of 12, 15 and 16.5 Ch. To disintegrate the stone, a pneumatic lithotripter and a holmium laser "Auriga" with a fiber of 365 and 600 μm in diameter were used. Only in 31 cases, when the kidney size allowed, a standard 24 Ch nephroscope and combined lithotripsy (ultrasound and pneumatic) were used. The duration of the procedure varied from 32 to 145 minutes, with an average of 43.5 minutes. In the postoperative period, all patients underwent infusion and antibiotic therapy based on the results of urine bacteriological examination. After the patients’ activation on days 1 – 3, a survey urography and antegrade pyeloureterography were performed. In the absence of residual stones and urinary passage disorders, nephrostomy drainage was removed.

Results. The effectiveness of nephrolithotripsy in our cohort of patients was 87.1% (81 patients). Four children (4.3%) required second percutaneous intervention. The remaining 8 (8.6%) patients with residual stones underwent distance lithotripsy in the short postoperative period. Significant bleeding occurred in 2 patients who then required transfusion of blood products. Fever was noted in 5 (5.4%) patients. We have not observed a single case of septic and bacteriotoxic shock.

Discussion. As a first-line surgical treatment in pediatric practice, it is recommended to use extracorporeal shock wave lithotripsy (ESWL). This treatment is ideal for stones ≤ 15 mm in size, with SFR of 68-95%. However, the need for repeated ESWL sessions occurs in 14-54% cases. Complications rate, frequency of retreatment, as well as a decrease in SFR, increase when a stone size is greater than 1.5 cm. Since all types of surgical treatment in children require anesthesia, and the treatment approach may not provide a complete problem solution, it is preferable to choose a procedure with the greatest possible success in one session. Primary SFR was significantly lower in children with stones ≥ 30 mm in size and multiple kidney stones. Mini– percutaneous nephrolithotripsy is an effective (87.1%) method for nephrolithiasis treatment in children aged 1 to 3 years.

Conclusion. Mini-percutaneous nephrolithotripsy in children aged 1 to 3 years is an effective treatment for nephrolithiasis. However, in a small percentage of cases, it becomes necessary to combine the procedure with extracorporeal lithotripsy. Paying attention to the small size of the organ, to reduce the number of hemorrhagic complications, it is preferable to perform this intervention with one approach. The occurrence of even a small amount of bleeding during the operation is a formidable complication, given the small volume of circulating blood in children.